header .header_bottom .nav>ul{
  width: 800px;
  height: 40px;
  display: flex;
  /*border: 1px solid green;*/
}
header .header_bottom .nav ul li{
  height: 33px;
  margin: 0 50px;
  line-height: 40px;
}
header .header_bottom .nav .second_sheet:hover{
  padding-bottom: 4px;
  border-bottom: 3px solid #fff;
}
header .header_bottom .nav ul li a{
  color: #fff;
  font-weight: bold;
}
header .header_bottom .nav #home_page{
  border-bottom: 3px solid #fff;
}
header .header_bottom .nav .art_class{
  width: 140px;
  height: 210px;
  /*border: 1px solid green;*/
  position: absolute;
  left: -42px;
  background-color: #fff;
  display: none;
  /*display: flex;*/
}
header .header_bottom .nav .art_class li{
  height: 50px;
  margin: 2px 0;
  text-align: center;
  line-height: 50px;
}
header .header_bottom .nav .art_class li a{
  color: #1f1f1f;
  font-size: 15px;
}



header .header_content .phone_scanning{
  width: 240px;
  height: 240px;
  line-height: 30px;
  position: absolute;
  top: 60px;
  left: -160px;
  text-align: center;
  display: none;
  background-color: #fff;
}
header .header_content .phone_scanning p{
  margin: 10px 0;
  height: 40px;
  line-height: 40px;
}
header .phone_version:hover .phone_scanning{
  display: block;
}